1. Field of the Invention
This invention relates to a data acquisition system for collecting data which are useful for the analysis of a malfunction of an elevator.
2. Description of the Related Art
An elevator installed in a building is essential ascending and descending means for the residents of the building and also for visitors to the building. If the elevator fails or malfunctions, their daily life will be crippled, with a potential danger of fatal accidents. To prevent such an elevator malfunction, and if it occurs, to promptly eliminate it, a building with an elevator installed therein is provided with a terminal supervisor unit connected to a control system for the elevator and the terminal supervisor unit is in turn connected via a telephone line or network to a supervision center of an elevator maintenance services company. The terminal supervisor unit constantly receives and stores data indicative of the state of operation of the elevator from the control system for the elevator and based on the operational state data so received, determines any malfunction. If a serious malfunction occurs, the terminal supervisor unit additionally stores data which have been relied upon for the determination of the malfunction, and transmits via the telephone line or network the thus-stored additional data along with the place of the occurrence of the malfunction, the code number of the elevator in question and the kind of the malfunction to the supervision center.
Upon receipt of a report of such a malfunction from one or more of terminal supervisor units for a number of elevators under supervision, on the other hand, the supervision center dispatches a maintenance service man or crew to each site, as needed, to eliminate the malfunction. In addition, the cause of the malfunction is analyzed based on the received data and is used as a reference or guide for future maintenance work in order to avoid occurrence of the same difficulty.
In the conventional terminal supervisor unit described above, a particular malfunction is determined to have occurred when a set of data relevant thereto have assumed predetermined states, respectively. If passenger(s) are confined to an elevator car, for example, there are inputted, as data which determine such a malfunction, "passenger(s)" data (i.e., data on whether or not there are passengers(s) in the car), "sudden stop during running" data (i.e., data on whether or not the car suddenly stopped during running" and "time" date (i.e., data on whether or not a predetermined time has elapsed subsequent to the sudden stop). If these data indicate "passenger(s) in (the car)", "suddenly stopped" and "30 seconds elapsed" a passenger trapped malfunction is determined to have occurred. At the time point of this determination, relevant data are additionally stored.
The operation of the above prior art device in the case of a trapped passenger malfunction will be described with reference to time charts illustrated in FIGS. 1 and 2, respectively. Observing the situation at time t.sub.1 in FIG. 1, there is neither "passenger detection" nor "sudden stop during running". The situation therefore does not meet the conditions described above. Whereafter, at time t.sub.2, the situation of "passenger(s) in (the elevator)" and "suddenly stopped during running" have arisen so that at this time t.sub.2, a timer begins to count the time. When 30 seconds have elapsed since that time as counted by the timer ("30 seconds elapsed") and time t.sub.3 is hence reached, the situation of "passenger(s) in (the elevator)" "suddenly stopped during running" and "30 seconds elapsed" has arisen so that a caging-in trouble is determined to have occurred. In response to this determination, in addition to the data of "passenger(s) in (the elevator)" and "suddenly stopped during running", relevant data at this time are collected and are once stored in a storage unit.
Incidentally, the purpose of interposing the time interval (for example, 30 seconds) since the occurrence of "suddenly stopped during running" until the determination of occurrence of the trouble is to corroborate the occurrence of a malfunction. For example, although the elevator is in order, the data of "passenger(s) in (the elevator)" and "suddenly stopped during running" may occur for certain reasons or at the moment that a power supply is turned on, such data may occur. The data however do not last for more than a certain time in such a case. The interposition of 30 seconds therefore makes it possible to avoid erroneous malfunction reporting.
FIG. 2 partially illustrates the relevant data (referred to above) at time t.sub.3. In FIG. 2, "running corroboration" represents a signal indicating whether or not the car is running whereas brake designates a signal indicating whether or not a brake has been applied. On the other hand, "open zone detection" means a signal indicating whether or not the car is located within a zone of a vertical shaft (i.e., open zone) which is preset on both upper and lower sides of the floor of each elevator hall to permit opening of the door within the zone. "Open door detection" denotes a signal indicating whether or not the door has been opened (the hatching indicates that the door is open). Further, the "safety device actuation" designates a signal indicating whether or not a safety device such as a governor switch provided for the detection of any abnormal speed of the car or a final limit switch provided for the detection of passage of the car beyond a top floor or a bottom floor has been actuated (the hatching indicates that the safety device has been actuated). It is apparent that these signals shown in FIG. 2 are only a portion of the many types of data which may be collected. As is evident from the time chart, the relevant data to be stored are the "open door detection" data and the "safety device actuation" data.
The data stored as described above are transmitted to the supervision center, along with data such as the place of the occurrence of the malfunction, the code number of the elevator in question and the nature of the malfunction. By analyzing the thus-transmitted data in detail, it is possible to use them for the investigation of the cause of the problem and based on the investigation, to establish a measure for the prevention of occurrence of the same malfunction in the future.
Although a malfunction may occur suddenly, a certain sign of the malfunction is observed beforehand in many instances. In this case, the data transmitted as described above are insufficient for the more accurate investigation of the cause of the malfunction because they consist of only the data which were employed for the determination of the malfunction at the time when it was determined to have occurred. That is, relevant diagnostic information based on events which occurred before the malfunction was determined to exist are not transmitted or available.